Reflective displays, such as liquid crystal displays, require a light guide structure to emit white light toward their display panel. One conventional light guide structure is configured such that yellow fluorescent substances are excited by blue light emitted from a blue light-emitting diode (“LED”). This structure mixes yellow light from the yellow fluorescent substances with the blue light from the blue LED to produce white light. In this conventional structure, it is difficult to find to proper balance between the blue light and the yellow light. This can easily result in color unevenness. Another problem with this conventional structure is low color purity, because the produced white light is pseudo white light based on the combination of the blue light and the yellow light. Yet another problem is that it is not possible to freely change an emission intensity of the pseudo white light, nor is it possible to make the pseudo white light have various colors. A still further problem is that when the yellow fluorescent substances are not transparent, the non-transparent fluorescent substances act as scattering particles. This makes it difficult to propagate excited light within the light guide structure from an edge of one side to an edge of an opposite side. Given these circumstances, expectations for a light guide structure configured to emit white light with a high level of color purity have increased in recent times.